Light-emitting diode (LED) devices has experienced rapid growth in recent years. LED devices emit light when a voltage is applied. LED devices have increasingly gained popularity due to favorable characteristics such as small device size, long lifetime, efficient energy consumption, and good durability and reliability.
The fabrication of LED devices may involve a die-to-wafer bonding process, in which a plurality of LED dies are bonded to a plurality of bonding pads on a wafer. Conventional die-to-wafer bonding processes use auto die-bonding machines with a flux reflow oven or eutectic die-to-wafer bonders. During the bonding process, LED dies shift their lateral positions with respect to the bonding pads in any given direction. In some cases, the die-shift may exceed +/−38 microns. As the LED die size continues to decrease, the die-shift of conventional LED bonding processes is becoming a bigger issue because the reduction of reliability and performance for smaller LED devices is greater.
Therefore, although conventional LED die-to-wafer bonding processes have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.